Stalling In Turns

[crdpoker]

Hi Guys,

Weird problem, and I'm looking for a little help. I've got an 85 6.2L GMC Jimmy (Same as K5 blazer) which has been giving me fuel problems. The previous owner had completely botched a fuel line replacement job, cutting out bad parts, and replacing only certain segments with rubber hose. The entire line from tank to lift pump probably had 4 separate splices in it, with cheap hoseclamps on each part of it.

As you probably guessed, I had air problems. The truck only ran decent with a full tank, and even then, if you let it sit in a nose up position (going uphill), it would suck air, and stall, refusing to restart until you bled it at the firewall filter.

I finally fixed it two weeks ago, installing a universal electric lift pump (cube style from autozone) at the tank, and 1 continuous piece of line from lift pump to the stock stanadyne firewall filter. At first it ran absolutely great, and I thought all my problems were solved.

But now the truck is stalling at really odd times, mostly when you turn the wheel. On my drive to work, I make a decelerating right turn onto a street, where the truck dies every single day. Once you pop it in neutral, it fires right back up, and runs perfectly. Also, when parking or parallel parking, turning the wheel right and left will sometimes stall it as well.

Because it fires right back up so perfectly, I don't think I'm still getting air problems. Is it possible this lift pump's PSI output is too low for the DB2 at low rpms after getting off the gas? Could it just be a fuel filter problem? Is my idle set too low?

Any help would be appreciated, this is really driving me crazy.

-Chris

[DmaxMaverick]

First, verify your filler cap is venting. If it isn't, it will cause all kinds of problems, including what you are experiencing. Loosen or remove it and try to duplicate the problem. A gasser fuel cap will do this, too. You need to have a Diesel fuel cap that vents in both directions. This issue gets worse with less fuel in the tank (more profound fuel expansion/contraction), and overnight parking position.

As far as fuel PSI goes, if anything, it will be too high. If you installed a "universal" pump, it is probably over pressuring the system. The Stanadyne IP requires essentially no pressure, just supply that doesn't allow IP suction (negative pressure). Good working fuel pumps should be in the 4-7 PSI range (under demand), more typically near 4. 10 PSI is max. Many under full load will get down to less than 1 PSI, but that's OK. Too much pressure will cause timing issues. The DB/DS pumps will run under low power demands w/o a lift pump. If your electric pump is not free flowing w/o power, it may also be suspect. If you keep the electric, get the right Diesel fuel pump, and make sure you have a failsafe included in the system (stops fuel when the engine is off or quits).

If you have an issue tied with just turning the wheel (not actually centrifugal force of the vehicle, like parking????), then it's not a pressure problem. You have some physical intervention (or electrical interruption if the lift pump doesn't bypass). It could also be a PS pump or hydroboost problem, stalling the engine under certain PS pump demands, as turning and braking at the same time causes the highest pump demand. Doubtful, though.

Check the system for steering components that may come in contact with any part of the fuel system at full lock. If a tire contacts a fender liner, check behind it. Could be pinching a fuel hose. Doesn't explain the whole issue, though.

Could also be the fuel pickup/sender in the tank, but I doubt it. Check everything.

[joe bleaux]

My bet is a wire is being rubbed with some linkage, effectively grounding the fuel pump.

Joe



Hi Guys,

Weird problem, and I'm looking for a little help. I've got an 85 6.2L GMC Jimmy (Same as K5 blazer) which has been giving me fuel problems. The previous owner had completely botched a fuel line replacement job, cutting out bad parts, and replacing only certain segments with rubber hose. The entire line from tank to lift pump probably had 4 separate splices in it, with cheap hoseclamps on each part of it.

As you probably guessed, I had air problems. The truck only ran decent with a full tank, and even then, if you let it sit in a nose up position (going uphill), it would suck air, and stall, refusing to restart until you bled it at the firewall filter.

I finally fixed it two weeks ago, installing a universal electric lift pump (cube style from autozone) at the tank, and 1 continuous piece of line from lift pump to the stock stanadyne firewall filter. At first it ran absolutely great, and I thought all my problems were solved.

But now the truck is stalling at really odd times, mostly when you turn the wheel. On my drive to work, I make a decelerating right turn onto a street, where the truck dies every single day. Once you pop it in neutral, it fires right back up, and runs perfectly. Also, when parking or parallel parking, turning the wheel right and left will sometimes stall it as well.

Because it fires right back up so perfectly, I don't think I'm still getting air problems. Is it possible this lift pump's PSI output is too low for the DB2 at low rpms after getting off the gas? Could it just be a fuel filter problem? Is my idle set too low?

Any help would be appreciated, this is really driving me crazy.

-Chris

[Rytari]

i must tell you same kind of issue from years ago... i had custom cruiser W/ 5.7D... and it stalled EVERYtime when driving downhill, i had to roll down , stop and start it again... if car were even slightly nose down, it refused to turn on no matter how long you started it... but if i manage to get it level, or more better if nose little up (1" enought :) ), it came to live asap.

only way to keep it running: hold pedal at same position (at all cost) before coming to hill... and quess how fast i was going sometimes :)

never found the problem...

this is just small flash in my memory, not supposed to hammer your hope down, sorry

[crdpoker]

Finally got this taken care of after having the truck parked for awhile. I realized my problem wasn't so much the turning of the truck itself, but when the wheel was moved to a certain position, the truck would turn off. I had a lot of slop (a LOT!) in the wheel, due to it being a mid-80's tilt column GMC. The tilt wheels are notorious for getting "jiggly" in their old age, and mine was no exception.

In fact, it was so bad, that this was the cause of my stalling. The ignition is actually mechanical in the steering column, so in a certain position, it was acting like I turned the key backwards for a brief second. Rebuilding the steering column and tightening the 4 loose (actually 3 completely unscrewed, only 1 half in) bolts fixed my problem. Good luck to anyone who ever experiences the same thing, those steering columns are fun!

Chris

[DmaxMaverick]

Good deal!

BTW....There is a tool for R/R of the wheel lock plate spring and circlip. Unless you really like bloody fingertips, it's the way to go.

[Robyn]

Yes for sure for sure, those lock plate keepers are a nasty lot without the pusher tool.

The issue with these tilt assemblies is the 4 little bolts that hold the pivot mechanism to the main column come loose.

You can clean these up with brake kleen and use a small drop of "BLUE" locktite on the threads to stop them from backing off again.

Best

Robyn